Photographing light trails of traffic

What you need

You just need your SLR, a tripod, cable release and a place to work that’s
not in the path of a whole bunch of speeding cars.

Settings

This is one of those times that just screams “B” in your mode dial. That
“B” stands for “Bulb” mode. When your camera’s in bulb mode
the shutter stays open for as long as you hold down the shutter button.

Focus

When you press the shutter button you don’t want your camera hunting for focus in
the dark. So it’s best to focus your camera manually. In the photo above I was
using a wide-angle lens, which automatically gives a big depth of field, and I focused on
a point just before the horizon.

ISO

Modern cameras are so good in low light now that you can almost shoot in the dark.
But to get a nice long light trail we need the exposure to run for several seconds. That means
we won’t be taking advantage of the high ISO levels available in our cameras. I set my ISO to
my camera’s minimum, which was 100.

Tripod

The moment you mention long exposures you have to think about a way of keeping your
camera rock-steady, so I use a tripod.

Cable release

Mechanical (left) and electronic (right) cable releases. Personally I prefer
the old-fashioned mechanical cable releases because they are so simple they never fail, but a lot
of modern digital cameras won’t work with them these days. The modern electronic ones,
are full of complicated electronics that might not last forever. And the electronic ones
are not only more expensive, but each one only works on a small number of cameras because camera
manufacturers keep changing the design of the port/plug in their new cameras, forcing
us to buy another damn cable release each time. Your camera’s manual should tell you what kind
of cable release works with your camera.

The moment you mention long exposures you usually also need to think about a cable release.
What’s a cable release? It’s a cord with a button at one end
and you plug the other end into a special port/hole in your camera. From then on, pressing the button
at the end of the cable is like pressing the shutter button on your camera. The vibrations you
create when you press the shutter button on the cable fail to travel all the way down the cord
and so you avoid jiggling your camera during your long exposure, resulting in much sharper photos.

Take a test shot

If it’s dark already then try a test shot. Wait for some cars to drive into your
camera’s field of view and then try something like a 5-second exposure to see if
that captures sufficient lengths of light trails. In other words, you squeeze the shutter button in on
your cable release when some cars drive into a good bit, and don’t let it go for 5 seconds.
In my case the light trails I got weren’t long enough with 5 seconds so I did
an 8-second exposure and was much happier with it. I’m not being super-precise here — I just count the
seconds in my head. You don’t need to be any more accurate than that.

Cars’ tail lights and headlights are super bright so your camera should have
no problems recording their trails when the cars move. With exposures lasting that long,
don’t expect to see much of the cars though. Remember that the cars will be smeared
across just as much of the frame as the light trails. So they will most likely be invisible.

Remember too, if you let your exposures run for really long times then not only will get
very long light trails, but the rest of the scenery should start becoming visible in your shots too.